Bicycle chain

I'm not really into DIY and maintenance stuff, so when I bought this bike I decided to try hub gears. The hub is awesome and looks after itself just great, but not having a derailleur to tension the chain I suffer from the chain falling off when it stretches. Today it fell off twice in my lunchtime cycle to Los Cardos. :(

To fix this I need to move the rear wheel back slightly to take up the slack every few months. Eventually I can't move the wheel back any further, and I need to start removing links from the chain instead. Maybe if I looked after the chain better it wouldn't stretch so quickly, but preventative maintenance isn't my style.. :)